1. Technical Field
The present invention relates to medical devices, particularly surgical instruments and prostheses, having elongated and generally opaque wall structures surrounding an elongated lumen such as catheters, introducers, needles, stent frames and stent grafts. The invention particularly relates to methods and apparatus for applying selected coatings to endolumenal surfaces of such devices.
2. General Background
Catheters, introducers, and other similar medical devices having elongated lumens are used to deliver diagnostic and therapeutic agents and appliances to remote locations through the vascular systems within the body of a patient. Needles, stent frames, stent grafts and other similar medical devices have elongated, although, generally, proportionally somewhat shorter lumens that are used to provide a pathway for vital fluids to and through the tissue and vascular systems of the patent. Further, when expanded radially, stent frames have a more or less porous structure rather than the substantially continuous wall character of the other medical devices considered herein.
Considerable attention has been given to controlling the physical interaction between such devices and the various structures and fluids through which the devices are moved by manipulating the surface chemistry of various portions of the devices. For example, U.S. Pat. No. 6,706,025 to Engelson, et al., discloses coating various longitudinal segments of the exterior surface of a catheter with lubricious hydrophilic polymers selected to provide various frictional characteristics to the different longitudinal segments. The selected polymeric coatings are applied by spraying a solution or suspension of the polymers or of oligomers of the monomers onto the catheter, or by dipping the catheter into the solution or suspension after sealing the open ends of the catheter. The coating is allowed to dry. During or after drying, the coating can be irradiated with ultra-violet light or ionizing radiation to promote polymerization and cross-linking of the coating to the exterior surface of the catheter. The coating procedure can optionally be repeated so that one or more additional coatings are applied in a similar manner. No means are disclosed to specifically apply any coating liquids to the endolumenal wall of the catheter. No means are disclosed to provide irradiation to encourage the polymerization of any coating fluids that might accidentally flow into the lumen of the catheter. As a result, the interior surface chemistry of the catheter is essentially totally unaffected by the procedures and chemical agents disclosed in Engelson.
Other processes for coating stent frames are known from including brushing, wiping, pad printing, ink-jet printing, electrostatic liquid spraying, and electrostatic powder coating. The desirability of coating stent frames with a polymer dissolved in a solvent optionally containing a therapeutic substance such as actinomycin D, paclitaxel, docetaxel, or rapamycin is known. Known polymers that can be used to coat stents with such substances include, for example, a number of polymethacrylates, polycaprolactone, and polysilanes. The therapeutic substances can also be anti-neoplastic agents, anti-proliferative agents, anti-inflammatory agents, growth control factors, antibiotics, antioxidants, and combinations thereof.
However, there remains a need for methods and apparatus to apply a desired surface chemistry to the endolumenal walls of catheters, introducers, needles, stent frames, stent grafts, and other similarly structured medical devices, to achieve the recognized benefits of such modifications in surface chemistry. There is a particular need to coat the endolumenal walls or surfaces of stent frames and stent grafts with substances that will effectively inhibit targeted adverse physiological reactions, such as restenosis, caused by uncoated surfaces of medical devices inserted or implanted in a patient's body.